Strain-relief grommet



Dec. 29, 1953 G. M. RAPATA STRAIN-RELIEF GROMMET Filed Jan. 11. 1952Patented Dec. 29, 1953 STRAIN-RELIEF GROMMET George M. Rapata, Chicago,Ill., assignor to Illinois Tool Works, Chicago, Ill., a corporation ofIllinois Application January 11, 1952, Serial No. 266,018

7 Claims.

This invention relates generally to strain-relief grommets and moreparticularly to grommets of the type made of electrically non-conductivematerial to support, insulate, and otherwise protect electricalconductors, rods, or tubes extending through apertured panels.

The type of strain-relief grommet or gripping insulator contemplated bythis invention may be quickly and easily applied from one side of anapertured panel. The design of this fastener permits it to bepreassembled on a panel and thereafter the conductor threaded throughthe grommet before the grommet is finally positioned relative to thepanel on which it is mounted. The grommet contemplated by this inventionis adapted to grippingly engage the conductor passing therethrough whicheliminates movement of the electrical conductor relative to the panel aswell as wear of the insulation if such is used on the conductor.

It is an important object of this invention to provide a comparativeli7small unitary fastener which is designed to be applied from one side ofan apertured panel and grips and supports a conductor or the like inangular relation to the panel through which it passes.

It is one of the important objects of the present invention to provide astrain-relief grommet which may be preassembled within the aperture of apanel or work piece and thereafter expanded into tight fitting relationwith resp-ect to the work piece and with respect to an elongated membersuch, for example, as an electrical conductor extending through andprojecting from opposite extremities of the grommet.

More specically, the invention contemplates a strain-relief grommet ofthe type referred to above which, when it is expanded into tight ttingrelation with respect to a work panel, also contracts into tightgrip-ping relation with respect to the periphery of the elongated workpart.

, It is also an object of the present invention to provide a gronimet orfastener as set forth above, wherein the expansion of the grommet intotight fitting relation with respect to the panel, and the contractionthereof with respect to the elongated work part or conductor, may beaccomplished by a single element driven into telescopic association witha hollow rivet section.

It is another object of this invention to provide a strain-reliefgrommet wherein the member which grips the outer periphery of theconductor also serves as means for expanding the rivet portion of thefastener into permanently mounted position with respect to the panel.

It is still a further object of the present invention to provide afastener of the type described which is adapted to be preassembled to anapertured panel prior to the passng of the conductor therethrough, thusenabling an operator to mount a plurality of these devices or grommetson a panel, thread Wires therethrough and thereafter secure thefasteners upon the panel in gripping engagement with the conductor.

1t is another object of dhe present invention to provide a fastener ofthe type described which is designed to be preassembled on a conductoror the like without first longitudinally feeding the conductor through acentral passage in the fastener, and to this end the fastener is adaptedto receive a conductor inserted laterally thereof.

Still another object or" this invention is to provide a strain-reliefgrommet which, when finally mounted on an apertured work part,substantially seals the aperture into which it is inserted.

These and other objects of the invention will be more apparent from areading of the following description and a study of the accompanyingdrawings, wherein- Fig. l is a perspective View of a work piece or panelhaving strain-relief grommets of the type contemplated hereby mountedthereon;

Fig. 2 is an enlarged end View of one of the grommets as viewed from therear of Fig. 1;

Fig. 3 is a perspective view oi one form of the fastener contemplated bythis invention;

Fig. 4 is a cross-sectional view of the fastener shown in Fig. 1preassembled on an electrical conductor and ready to be mounted on anapertured work part;

Fig. 5 is a sectional View of the fastener shown in Fig. 4 after beingpreliminarily positioned on the apertured work piece;

Fig. 6 is a sectional View of the fastener shown in Figs. e' and 5 infinally applied position with the stud portion of the fastener mountedin the work part and the electrical conductor grippingly engaged, saidview being taken substantially along the line S- of Fig. 2;

Fig. 7 shows a second embodiment of the invention wherein the grommet isprovided with a resilient head member; and

Fig. 8 shows still another embodiiient of the invention wherein agrommet of the type contemplated by this invention is designed to acceptan electrical conductor through a sidewall ther-L of, eliminating thenecessity of threading the conductor longitudinally through the grommetmember.

, Referring to the drawings wherein like nufrom one of the resilientiingers 24h moves into registration with that portion or' the sideopening 3@ in the rivet head ih. in this manner the lrey 33 serves tocompletely seal the rivet within the work aperture and the rivet headgives the appearance of being a complete or solid head. By having theside openings oi the rivet section and sleeve circumferentiallydisplaced from each other, the registration of these openings with eachother after the parts have been driven into final tightened position isprevented.. This assures trapping of the conductor or similarlongitudinal element within the groinrnet structure. This type ofstrain-relief grommet is useful in applications where it is desirable tomount a fastener on a wire intermediate its ends. In other words, thereare many instances where the end of the conductor is not accessible tothe operator, and thus cannot be threaded through the grommet. In suchinstances the side opening arrange -c ment in the grommet serves a veryuseful purpose. While several embodiments of the invention have beenshown, it should be understood that this invention is capable of otherinodcations and changes without departing from the spirit and scope ofthe appended claims. Thus, the invention is not limited to the specificforms ilius.. trated herein, but should he limited only by the scope ofthe claims.

The invention is hereby claimed as follows:

l. A strain-relief, electrically non-conductive grominet foraccommodating elongated members, such for example as electricalconductors, including a hollow rivet section consisting of a shank, ahead at one extremity oi said thank for engaging one side oi anapertured Work piece, a transversely yieldahle portion at the other endof said shani-z adapted to 'oe expanded into engagement with theopposite side of the aforen mentioned apertured work piece, and atubular section normally projecting from the head ezitremity of saidrivet section in position to oe driven into telescopic associationtherewith, :aid tubular section normally having substantially constantinternal and external diameters throughout a substantial portion oi' itslength, the outer extremity of said tubular section fiaring radiallyoutwardly and axially severed to assure inward flexing and consequentimpingement of the inner periphery thereof with a coinplenientaryelongated member as an incident to telescopic association of the rivetand tubular sections.

2. A groinmet or the type described in claim 1, wherein the head of therivet section 'presents an annular shoulder having its clamping surfaceundercut to provide a seal when the fastener is mounted on an aperturedWork part.

3. A grommet oi the type described in claim i, wherein the rivet andtubular sections are pro-- vided with side ports communicatin" withtheir interiors and completely traversing their longitudinal axes, theport in the tubular section being circumferentially displaced from and cminuni4 eating with the port in the rivet section wheren by to permitlateral insertion of an clongaged member such as an electrical conductorthrough said port into the interior oi' the rivet and tubu lar sections.

4. A groininet of the type described in claim l, wherein the rivet andtubular seclions are provided with side ports communicating with theirinteriors and completely traversing their longitudinal axes whereby topermit lateral insertion of an elongated member such as an electricalconduotor through said ports into interior o3? the rivet and tubularsections.

5. A grommet or the type described claim 2, wherein the head of therivet recessed to assure yielding of the head and engagement ci theclamping surface with a workpiece provide a seal.

6. A strain-relief grommet for accommodating elongated members,comprising a hollovvv rivet section including a shank, ahead at oneextremity of said shank ior engaging one side of an apertured workpiece,a transversely yieldahie portion at the other end ci said shank adaptedto he panded into engagement with the oppos" e side of an aperturedworkpiece, and a tubular section normally projecting from the head ofsaid rivet section in position to be driven into teiescopi associationtherewith, said rivet and tubular sections having side portscommunicating with their interiors and completely traversing theirlongitudinal axes whereby to permit lateral insertion of an elongatedmember through said ports into the interior of the rivet and tubularsections.

'7. A grommet as deiined in claim 6, which includes a key memberextending radially from the outer end of said tubular section andinsertable in the portion of the side port extending through the head ofthe rivet section When the rivet and tubular sections are moved intotelescopic relationship.

GEORGE M. RAPATA.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,462,287 Kearns June 18, 19.45 2,424,602 De Swart July 29,i947 2,530,258 Marsan Nov. 14, i) 2,592,130 Erb et al. Apr. 8, 1952

